Treatment of motor fuel



Patented Aug. 6, 1935 UNITED STATES PATENT OFFlCE 2,010,029 TREATMENT OF MOTOR FUEL Jacque C. Morrell and Charles G. Dryer, Chicago,

Ill., assignors to Universal Oil Products Company, Chicago, 11]., a corporation of South Dakota No Drawing. Application January 11, 1932, Serial No. 586,072

12 Claims. (Cl. 44-9) This invention relates to the treatment of motor might be discovered which would inhibit sepfuels, and refers more particularly to the treatarately the formation of gum, color or decrease ment of cracked distillates of gasoline boiling in knock rating, although in most instances it has range or those containing a substantial proporbeen found that the development of gums and tion of gasoline, such distillates being generally color and loss in anti-knock value are closely. 5'

characterized by a relatively high knock rating. related so that whatever inhibits one type of More specifically the invention has reference change also inhibits the other. to processes of treatment whereby th deteriora- Inhibitors are to be distinguished from antition of such fuels on storage with respect to gum knock agents in thatthe true anti-knock agent formation, and particularly anti-knock value, is modifies the combustion of fuel in an internal 0 substantially prevented, under the varying influcombustion engine cylinder butdoes not necesence of light, air, et cetera, to which they are sarily prevent the development of undesirable subjected, characteristics under storage. In fact, numer- Prior to the advent of the cracking process as a 0115 known anti-knock agents are themselves un- 5 factor in the trade, the straightrungasolines prostable in storage and the gasoline to which they 15 duced either by simple distillation from crudes are added needs further additions of true inor by absorption from casinghead gases were of hi'bitors to stabilize the increased anti-knock an essentially saturated character, containing value produced by the addition of the anti-knock only negligible amounts of olefinic and cyclic hyagent. Furthermore, it is usually necessary to drocarbons so that they underwent substantially use much higher percentages of reagents to pre- 20 no change when stored for long periods of time, vent knccking than is necessary in inhibiting departicularly if reasonably protected frbm the interioration and depreciation of the gasoline so fluence of light and air. that it will be seen that in the great majority When cracked-gasolines became an important of cases the action of anti-knock agents is dis- 5 factor in the trade it was found that their more tinct from that of true inhibitors, the use of unsaturated olefinic constituents such as the di which constitutes the present inventionand tri olefins were characterized by a tendency to In one specific embodiment the present invendeposit gummy or resinous materials upon standtion comprises the use of coal tars or particular ing, particularly under the influence of light and fractions obtained in the distillation of coals or air and were objectionable constituents on acof tars obtained therefrom as inhibitors for pre- 30 count of this gum-forming tendency as well as venting the deterioration of the quality of gasoon account of their loss as possible anti-knock lines on storage. The invention has specific refmaterial due to the gum-forming or polymerizaerence to the use of the so-called low temperature tion reactions. During the gum-forming period coal tars, or distillates obtained therefrom.

in the storage of cracked gasoline a yellow to The by-product distillation of coal is an art 35 brown color sometimes develops which is distinctof long standing and the various types of comly undesirable from a sales standpoint. The prespounds produced in the process will be given only ent invention is directed to preventing the forbrief mention at this point. Of the hydrocarmation of these undesirable gums and colored bons produced members of the paraflin, ethylene,

compounds and the reduction in knock rating of acetylene and benzene series have all been iden- 40 the motor fuel, although it is to be particularly tifled, with the last-named group predominating, pointed out that gum and color formation and particularly in operations conducted at relatively reduction in anti-knock value are'not necessarily high temperatures for the manufacture of coal related and that the accomplishment of the two gas. and metallurgical coke. Associated with objects may not bebrought about simultaneously, these hydrocarbons of varying boiling point: are 45 that is,-they may be independent of each other. 11 rous oxygen-containing and sulfur-con- The field of choice for the selection of subta i r i i ig compounds and many nitrogen de'rivastances to act as inhibitors in preventing the detives of hydrocarbons, principally of a heterocyvelopment of undesirable characteristics in clic character.

cracked gasolines on storage is large and many The inhibiting value of particular fractions 50 individual chemical compounds have been found from coal tar has been foundto be in many cases "tobe of special value, their use, however, being much greater than that which might. be 'prelimited many times by their scarcity and high cost dictable based upon their analytical content of of manufacture. Furthermore, it is possible that known compounds, and it is this feature that 85 certain compounds or ,mixtures of compounds constitutes one of the principal points of the present invention addition to the fact that ,'fractions are more readily produced than the individual compounds which might be used as inhibitors, and are therefore cheaper. Furthermore, it is recognized that analytical procedures are inadequate to completely determine the composition of these complex high boiling mixtures and that compounds may exist whose composition is not precisely determinable which exert a powerful retarding effect on the deterioration of properties in gasolines. It may also be observed that frequently mixtures ofchemical compounds utilizable as inhibitors have a greater inhibiting value than would result from the mere addition of'properties so that altogether the use of what may be termed natural mixtures of blends of inhibiting substances as they occur in coal tar fractions has distinctly novel and useful features.

The invention further comprises the utilization of mixtures of components separated by treating coal tar fractions with caustic alkalies and later acidification, the mixtures in th s case being substantially free from materials unacted upon by bases. This preliminary separation step may be utilized in cases where heavy neutral tars are present in amounts sufficient to cause either gum, discoloration or cloudiness in the gasolines to which they are added.

It is also comprised within the scope of the invention to utilize as inhibitors the mixtures of basic material removable from coal tar fractions by treatment with dilute sulfuric acid, the compounds being released from acid combination by additions ofstrong alkali. The use of neutral oils as inhibitors resulting from, or remaining after; treatment with acids and alkalies is comprised within the scope of the invention.

The selection of a coal tar or coal tar fraction for use in preventing the deterioration of any given gasoline on storage will be determined by consideration of a large number of factors. Primarily, the chemical composition of cracked and straight-run gasolines from difierent sources will vary markedly in respect to the percentages of those classes of compounds which require stabilization by the use of inhibitors. For example, whencracked gasolines are produced under relatively high temperatures and low superatmospheric pressures by processes currently known as vapor phase cracking processes, the percenages of di and tri olefins may be relatively high resulting in a pronounced tendency toward polymerization with attendant depreciation in value of the gasoline stock. In such cases more highly efficient coal tar fractions may be used, and. percentages of--the order of from possibly 0.01 to 2.0%. When more nearly saturated gasolines are produced from intermediate petroleum dis-' tillates of a relatively saturated character and.

imder higher supera'tmospherric pressures and lower temperatures, either smaller amounts of the more efficient fractions or the same amounts of relatively less efficient may suflice to eifect the required stabilization of properties. In most cases the proper selection will be readily made by a few experiments and present no unusual difficulties.

'I'o indicate the merits of the invention some experimental data may be introduced to show the results obtained by the use of coal tar fractions characteristic of the present invention. In obtaining the'data shown in the succeeding tabulation use was made of the oxygen bomb test which at the present time is quite generally accepted as a measure of the tendency of gasolines to deteriorate on storage, an induction period of four hours preceding measurable oxygen absorptionhaving been arbitrarily adopted as indicating a sufficiently stable gasoline:

The gasoline utilized in the tests, the results of which are shown above, was produced by the cracking of a highly parafiinic fuel oil from the Pennsylvania field under approximately 300 pounds per square inch pressure and a maximum cracking temperature of 940 F. The gravity of the gasoline was approximately 61.0 A. P. I. and the end point 410 F. It is particularly to be observed from the table that the 250 to 275 C. fraction produced markedly better results than the other fractions tested, even when percentages as low as 0.01% were used.

The foregoing specification and examples have disclosed the nature of the present invention, but neither should be considered in the light of embodying limitations thereon, since it is evidently broad in scope and applicable in many other cases than the one given.

We claim as our invention:

'1. A process for reducing deterioration of cracked gasoline containing gum-forming unsaturates, which comprises adding to the gasoline a small amount of a coal tar fraction containing a suflicient quantity of constituents of the tar boiling between 200 C. and 325 C. to substantially inhibit gum formation in the gasoline.

2. A process for reducing deterioration of cracked gasoline containing gum-forming unsaturates, which comprises adding to the gasoline a small amount of coal tar distillate boiling between 200 C., and 325 C.

3. A process for reducing deterioration of cracked gasoline containing gum-forming un-.

saturates, which comprises adding to the gasoline a small amount of coal tar distillate boiling between 250 C., and 275 C.

4. Motor fuel comprising cracked gasoline stabilized against gum formation by the incorporation. thereinto of a small amount of a coal tar fraction containing a sufficient quantity of constituents of the tar boiling between 200 C. and 325 C. to substantially inhibit gum formation in the gasoline.

5. Motor fuel comprising cracked gasoline containing a small amount of a coal tar distillate.

8. A method for stabilizing cracked hydrocarbon motor fuel which comprises incorporating into the fuel a relatively small amount of a low temperature coal tar distillate containing alkalisoluble and alkali-insoluble-constituents of the coal tar and a suflicient quantity of constituents of the tar boiling between 200 C. and 325 C. to substantially inhibit gum-formation in the fuel.

9. A method for stabilizing cracked hydrocarbon motor fu'el which comprises incorporating into the fuel a relatively small amount of a low temperature coal tar distillate boiling between 200 C. and 325C. and containing alkali-soluble and alkali-insoluble constituents of the coal tar.

l0. Cracked hydrocarbon motor fuel to which a has been added a relatively small amount of a low temperature coal tar fraction containing alkali-solubleand alkali-insoluble constituents of the coal tar and a sumcient quantity of constituents of the tar boiling between 200 C. and 325 C. to substantially inhibit gum formation in the fuel. 11. Cracked hydrocarbon motor fuel to which has been added a relatively small amount of a low temperature coal tar distillate containing alkalisolubie and alkali-insoluble constituents of the coal tar and a suillcient quantity of constituents of the tar boiling between 200 C. and 325 C. to substantially -inhibit gum formation in the fuel.

12. Cracked hydrocarbon motor fuel to which has been added a relatively small amount of a low. temperature coal tar distillate boiling between 200 C. and 350 C. and containing alkalisoluble and alkali-insoluble constituents of the coal tar.

' JACQUE C. MORRELL.

CHARLES G. DRYER. 

